It surely does look as if it could have been some type of dray. It also looks like it could have been used just for grading driveways and lanes but that is doubtful just because it appear to be all on one level and if used for grading it most likely would have several boards together. The rows of nails are interesting. By the way the chains are on it now one has to wonder if that is the way they used it or just how they fastened the chain on to drag it there. What is the size of it? Are the 2 runners slanted on one end as if it were pulled that way and not catch anything or dig into the ground? The reason I and others suggested a dray is the picture below. These can really work nice for hauling logs or even lumber. One can even fill in those empty spots and make a stone boat out of the dray. Perhaps it is something they used for hauling a tank when gathering sap? several possibilities.